The following statement is true for internal rotation of the head:

Ans. is b, i.e. In majority rotation occurs in the pelvic floorThe prerequisites of anterior internal rotation of the head are well-flexed head, efficient uterine contraction, favourable shape at the midpelvic plane and tone of the levator ani muscles.The level at which internal rotation occurs is variable. Rotation in the cervix although favorable occurs less frequently. In majority of cases, rotation occurs at the pelvic floor. Internal rotation occurs earlier in multipara than primipara Rarely, it occurs as late as crowning of the head.